A punch biopsy is a common diagnostic procedure used for excision or procuring a tissue specimen for histopathological examination. Although any organ can be biopsied, biopsy punches are commonly used to take patient (human and animal patients) biopsies of skin and hair. Punch biopsies are usually done with a simple biopsy punch that includes two members: a handle and a cutting member made of steel. The cutting member is generally a hollow cylinder that is sharp at a lower edge. The punch biopsy procedure is initiated by pressing and rotating the biopsy punch against tissue at a desired location for the biopsy. The biopsy punch then is pulled back and a needle or tweezers are used to stabilize tissue cut by the biopsy punch. The stabilized tissue then is cut at a base of the tissue with scissors or a blade.
Although the biopsy punch is relatively easy to make and the punch biopsy procedure is relatively easy to perform, there are negative aspects of the biopsy punch and associated tissue cutting procedure. For example, needles typically are used in the biopsy punch cutting procedure to expose and stabilize the base of the tissue prior to cutting with the scissors or blade, or to dislodge a biopsied specimen from a chamber of the biopsy punch. In such scenarios, doctors are susceptible to accidentally sticking themselves or an assistant with the needle. Additionally, use of tweezers also can cause problems. For example, holding the tissue too firmly with the tweezers can compromise the usefulness of the tissue for histopathology by creating artifacts that may confuse histopathology results. Other problems with punch biopsy procedures may include inadequate sample removal. Due to bleeding and fear of pulling on tissue, a practitioner may cut the tissue too shallow. Shallow cuts produce insufficient biopsies due to part or all of the subcutaneous tissue being left on the patient (i.e., the entity/target undergoing treatment—may be a person or animal).
Punch biopsy procedures have also been used to harvest hair grafts for hair transplantation in a process called follicular unit extraction. The standard biopsy punches are less than ideal for hair transplantation. Hair transplantation requires that the hair bulge and bulb, which are located deeper than the upper epidermal layers, be removed. Standard biopsy punches, however, do not penetrate deeply enough to adequately remove the hair bulge and bulb. In ideal hair transplantation, the upper layers of tissue are left behind to minimize scarring while more tissue is taken below the skin surface. U.S. Pat. No. 3,577,979 attempts to address these problems by using a set of short prongs located inside a cutting member to pierce skin if a biopsy punch is rotated in a direction opposite the direction of the prongs. The short prongs, however, may damage a tissue specimen and do not provide a component to cut the base of the tissue. The short prongs stabilize the tissue for cutting by scissors. U.S. Patent Application Publication No. 2007/0232954 generates elliptical biopsies by oscillating two cutter blades which are curved sideways and flat from top to bottom using a motor drive. The device, however, produces only superficial biopsies, up to 4 mm deep, which leaves part of the dermis and subcutaneous tissue behind. Furthermore, due to the curved shape of the blades, the blades may fail to completely cut the tissue.